OBJECTIVES: 1. To continue the establishment of an interactive computer graphics facility for macromolecular model building, refinement and display of proteins, nucleic acids, enzyme-substrate and protein-nucleic acid complexes and related macromolecular entities. 2. To determine the structure of the Cro repressor protein of bacteriophage lambda and elucidate the molecular basis of the interaction with its lambda DNA operators. 3. To determine the structure of single strand DNA binding proteins and to understand the rationale for their preferred binding to DNA. 4. To continue the development of new techniques for protein structure refinement. 5. To carry out systematic structural comparisons of selected proteins in order to better understand protein folding and the evolution of protein structure and function. 6. To continue structural studies of other biologically relevant macromolecules.